Starting out you want to make simple droplet streams. Slowish well formed droplets that are regular make your life much easier.
I've heard of people using just about anything you can find lying around to make their droplets. Spoons, Eye Droppers, Turkey basters and IV Drip's to name but a few.
What I used was a 'tie-handle' food bag (tie handle because the handles are easy to hook over stuff and hang up) hanging from a broom handle between 2 kitchen cupboards. Poke a REALLY small hole in the bag (fine needle or piece of thin stiff wire) at the very bottom of the bag. Make sure there's nowhere for the drips to run down.
This works but the drops tend to be a little randomly placed. If your trying to get in close the depth of field is tiny and if your drops are not falling into it accurately then you will end up with lots of useless pictures due to focus issues.
To make collision pictures like :
You need something that will make 2 drops fall *almost* together. I use a Mariotte Siphon (credit here to Martin Waugh's blog http://www.martin-waugh.com/) however after making 3 or 4 of them I've come up with a modified setup that works well.
This is amazingly cheap (£3 to £5) and works REALLY well. Click through the image to see the notes that explain it all.
With a mariotte siphon the speed of the drips depends on the difference in height between the output (the pipe connector) and the bottom of the input straw in the bottle.
In theory you should raise/lower the straw that goes out the top to vary the drops but I found that fixing the pipes in place and sealing them and physically raising and lowering the whole bottle works better as you can seal the pipes better and not have leaks.
Also doing this with a decently long pipe coming out means you can move the bottle to refil it without moving the output (and consequently having to refocus your camera etc).
Then you just have to raise/lower the bottle until the stream of drips coming out is sufficiently fast. One thing you can do is use your flash to strobe the drops and see how far apart they are. When one is hitting the water you want a second to be halfway (or slightly more) down so that by the time the spout has formed the drop is hitting it.
It takes experience, experimentation, luck, (and a bit more luck) to get it right, and even then only one picture in 50 or more may come out right.
Next : Depth of field, focusing and stuff.